Refine your search:     
Report No.
 - 
Search Results: Records 1-18 displayed on this page of 18
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Seasonal patterns and control factors of CO$$_{2}$$ effluxes from surface litter, soil organic carbon, and root-derived carbon estimated using radiocarbon signatures

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Hirai, Keizo*

Agricultural and Forest Meteorology, 152, p.149 - 158, 2012/01

 Times Cited Count:31 Percentile:84.71(Agronomy)

Radiocarbon ($$^{14}$$C) signature was used to partition soil respiration in a cool-temperate deciduous forest. Heterotrophic respiration strongly correlated with soil temperature, but the magnitude of the response to soil temperature was different between SOC decomposition and litter decomposition. Autotrophic respiration appeared to correlate strongly with the phenology index rather than soil temperature. The information on the seasonal change about the contribution ratio of each source to the soil respiration is essential to understand the intrinsic temperature sensitivity of each source and the other factors controlling soil respiration.

Journal Articles

Use of carbon isotopes as tracer to estimate carbon dynamics in forest

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Hirai, Keizo*

JAEA-Conf 2010-001, p.80 - 83, 2010/03

no abstracts in English

Journal Articles

Use of $$^{14}$$C to study soil carbon cycling in beech forest

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Hirai, Keizo*

KURRI-KR-153, p.8 - 13, 2010/03

Soil organic carbon (SOC) is a complex of materials with different ages. An understanding of soil carbon cycling and thereby predicting its response to climatic change requires knowledge of both the inventory of carbon and the turnover times of SOC. In this study, chemical and density fractionation were examined to separate the organic matter collected from a beech forest into components with different turnover times. Mean residence time (MRT) for each fraction was estimated from its radiocarbon isotope ratio ($$Delta$$$$^{14}$$C) using the $$Delta$$$$^{14}$$C-MRT model. The results show that fractions separated by chemical fractionation with acid-alkali treatment have clearer difference in the isotope ratio than that by density fractionation. This means chemical fractionation is more adequate to estimate MRT composition for the beech forest soil. We also observed differences in the inventory and MRTs of carbon using chemical fractionation for two forests with different vegetation and the mean temperature. The results show that the difference in decomposed carbon flux from these two forests is attributed to the difference in MRT composition in each forest.

Journal Articles

Quantitative aspects of heterogeneity in soil organic matter dynamics in a cool-temperate Japanese beech forest; A Radiocarbon-based approach

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Miura, Satoru*; Saito, Takeshi*; Hirai, Keizo*

Global Change Biology, 15(3), p.631 - 642, 2009/03

 Times Cited Count:35 Percentile:73.07(Biodiversity Conservation)

Although it is well documented the possibility that global warming can lead to an acceleration of microbial decomposition of soil organic carbon (SOC), the magnitude and timing of this effect remains highly uncertain. The main reason is a lack of quantitative aspect of the heterogeneity in SOC biodegradability. To quantify the heterogeneity, we collected the soil and litter samples within a cool-temperate deciduous forest in Japan, separated chemically the samples into SOC fractions, determined their mean residence times (MRTs) based on the radiocarbon ($$^{14}$$C) measurements, and finally represented the soil as a complex of six SOC pools with different range of MRTs. Predicted response of the SOC pools to warming demonstrates that the rate of SOC loss from the fast-cycling SOC pool diminishes quickly because of the substrate availability; in contrast, the warming continues to accelerate SOC loss from slow-cycling pools with MRTs of 20-200 year over the next century.

Journal Articles

Evaluation of carbon cycle in forest by using radiocarbon as a tracer

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Saito, Takeshi*; Hirai, Keizo*

JAEA-Conf 2008-003, p.75 - 78, 2008/04

C-14 is an effective tracer in investigating the carbon dynamics in the environment. In this study, the measurements of C-14 in soil organic matter (SOM) in a deciduous forest were used to determine the turnover time and CO$$_{2}$$ production rate from SOM. In addition, monthly measurements of carbon isotopic ratios in soil-respired CO$$_{2}$$ and atmospheric CO$$_{2}$$ were conducted to characterize the seasonal variation of the contribution of each CO$$_{2}$$ source, such as SOM decomposition and root respiration.

Journal Articles

Radiocarbon-based estimation of soil carbon turnover in a cool-temperate beech forest

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Saito, Takeshi*; Hirai, Keizo*; Miura, Satoru*

Proceedings of International Symposium on Application of a Closed Experimental System to Modeling of $$^{14}$$C Transfer in the Environment, p.72 - 76, 2008/00

Recent debate has emphasized that our capacity to predict the response of soil organic carbon (SOC) to climate change depends on a clear understanding of the heterogeneity in SOC biodegradability. We collected soil samples from the Appi forest meteorology research site dominated by Japanese beech, separated the soil samples into three SOC fractions with a chemical method, and determined their radiocarbon isotope ratios using an accelerator mass spectrometry. The radiocarbon signatures allow us to estimate their turnover times (TTs), quantifying the rates of SOC decomposition. According to the estimated TTs, the SOC was distinguished into six SOC pools with distinct TTs of several years to $$>$$ 1000 years. The annual SOC decomposition rate was summed up to 0.47 kgC m$$^{-2}$$ y$$^{-1}$$, about a half of which was from the fastest-cycling pool (litter). Approximately 5% of SOC gave the over-millennium TTs, suggesting that this pool plays a role of a long-term carbon sequestration in the carbon cycle.

Oral presentation

Radiocarbon-based estimation of annual heterotrophic respiration in Appi beech forest

Koarashi, Jun; Atarashi-Andoh, Mariko; Miura, Satoru*; Saito, Takeshi*; Ishizuka, Shigehiro*

no journal, , 

no abstracts in English

Oral presentation

The Use of carbon isotopes to identify the origin of soil-respired CO$$_{2}$$ in beech forest

Atarashi-Andoh, Mariko; Koarashi, Jun; Ishizuka, Shigehiro*; Saito, Takeshi*; Hirai, Keizo*

no journal, , 

Soil organic matter (SOM) is the major reservoir of carbon in terrestrial ecosystems. Thus, to evaluate the CO$$_{2}$$ flux from SOM is an important step toward estimating the effect of environmental change on the terrestrial carbon cycles. In this study, we estimated the contribution of different soil CO$$_{2}$$ sources (SOM, litter and root) to CO$$_{2}$$ flux from the forest floor based on measures of carbon isotopic ratios in SOM, litter, soil-respired CO$$_{2}$$ and atmospheric CO$$_{2}$$ in a cool-temperate deciduous forest.

Oral presentation

Radiocarbon-based estimation of soil carbon turnover and its potential response to global warming

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Saito, Takeshi*; Hirai, Keizo*; Miura, Satoru*

no journal, , 

no abstracts in English

Oral presentation

Stability and vulnerability of organic carbon stored in Japanese forest soils

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro

no journal, , 

Accelerated release of carbon (C) previously stored in soils is considered one of the most important positive feedbacks from terrestrial ecosystems to the atmosphere in a future warmer world. We used 14C analysis following chemical fractionation to quantify the sizes and turnover times of C pools of Japanese forest soils. The $$^{14}$$C-based approach revealed higher variations of the family of MRTs soil by soil. The size of C pools that cycle slowly on timescales of 100-1000 years strongly correlated with the content of pyrophosphate-extractable Al. In contrast, faster-cycling C pools that turn over within decades showed a negative correlation with mean annual temperature at the sites. Our results suggest that C dynamics in the isolated SOC pools may be regulated by different mechanisms: temperature control on decadal cycling C versus mineralogy control on slower-cycling C, and clearly demonstrate that the forest soils will respond very differently to climate change over the next century.

Oral presentation

How long do Japanese forest soils store carbon in their surface horizons?

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro

no journal, , 

Soils are the largest carbon (C) reservoir in terrestrial ecosystems, and may act as both a source and sink of atmospheric CO$$_{2}$$ in response to climate change. Identifying the sizes and turnover times of soil organic carbon (SOC) pools is a crucial step to predicting the fate of soil C. Here, we used a $$^{14}$$C-based approach to quantitatively understand how much and how long Japanese forest soils store C in their surface horizons. We collected soil samples from deciduous forests, separated the samples into SOC fractions, and then determined their $$^{14}$$C ratios to estimate mean residence times (MRTs). The MRTs ranged from years to millennia, which revealed a different distribution of MRTs between the soils. We found that the total amount of C correlated positively with the size of the SOC pools cycling on time scales of $$>$$ 100 years, but poorly with the size of faster-cycling pools. The results suggest that the soils with higher C stocks do not necessarily have higher potential for CO$$_{2}$$ emission.

Oral presentation

Seasonal and spatial variations in carbon isotopic ratios in CO$$_{2}$$ respired from a beech forest floor

Atarashi-Andoh, Mariko; Koarashi, Jun; Moriya, Koichi; Nakanishi, Takahiro; Ishizuka, Shigehiro*; Hirai, Keizo*

no journal, , 

no abstracts in English

Oral presentation

Soil organic matter degradability in four Japanese forest soils

Moriya, Koichi; Koarashi, Jun; Atarashi-Andoh, Mariko; Moriizumi, Jun*; Yamazawa, Hiromi*; Ishizuka, Shigehiro*

no journal, , 

no abstracts in English

Oral presentation

Soil organic matter degradability in four Japanese forest soils

Moriya, Koichi; Koarashi, Jun; Atarashi-Andoh, Mariko; Moriizumi, Jun*; Yamazawa, Hiromi*; Ishizuka, Shigehiro*

no journal, , 

no abstracts in English

Oral presentation

Radiocarbon as a tool for understanding soil organic matter dynamics

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi*; Nakanishi, Takahiro

no journal, , 

no abstracts in English

Oral presentation

Temperature sensitivity of soil organic carbon decomposition in four Japanese forest soils

Moriya, Koichi; Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Moriizumi, Jun*; Yamazawa, Hiromi*

no journal, , 

None

Oral presentation

A Radiocarbon-based approach to quantitative understanding of soil organic matter dynamics

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Kadono, Atsunobu*; Moriya, Koichi; Nakanishi, Takahiro

no journal, , 

no abstracts in English

Oral presentation

Quantitative understanding of the heterogeneity of soil organic carbon degradability for predicting long-term response of soil carbon to warming

Koarashi, Jun; Atarashi-Andoh, Mariko; Ishizuka, Shigehiro*; Hiradate, Shuntaro*; Kokubu, Yoko

no journal, , 

Microbial decomposition of soil organic carbon (SOC) is an important component of the global carbon (C) cycle, and even a small warming-driven change in the size and decomposition rate of SOC pools could significantly impact the atmospheric CO$$_{2}$$ concentration and thus the global C cycle. A quantitative understanding of heterogeneity of SOC degradability is essential for a reliable prediction of the response of soils to warming. While fast-cycling SOC pools dominate C fluxes from soils, the longer-term response of soils to warming will be largely determined by the sizes and turnover times of slow-cycling SOC pools in the soils, which can hardly be identified by conventional analytical and incubation methods. We attempted to characterize SOC pools with respect to their sizes and specific turnover times in Japanese forest soils, by a combinatorial use of SOC fractionation and $$^{14}$$C analysis. We represent the soils as a mixture of SOC pools with different turnover times ranging from years to more than a millennium, and on the basis of this representation and simple model calculations, we show the potential importance of slow-cycling SOC pools with turnover times of several decades to 200 years for the prediction of positive feedback to climate change over the next century.

18 (Records 1-18 displayed on this page)
  • 1